Not an overly accurate chart to use for our applications, especially seeing how it's based on 100 feet of pipe.

For example using a 1" pipe with a pressure drop of 4 feet will give an initial entrance velocity of about 16 f/s meaning before you consider pipe friction you'll get about 2300GPH. You can calculate your friction losses by yourself but you're not going to loose much more more than 25%.

Only thing I could find. Regardless I wouldn't be worried with 20-50gph running through my "emergency" drain.

You can use this calculator. It will tell you how much flow a pipe can take given diameter and head hight.

http://www.beananimal.com/articles/h...-aquarist.aspx

make sure you click the "Submerged Discharge" radio button in the calculator. That's a for Herbie or BA

I don't see anything odd about the plumbing setup. I think you're either trying to get it too perfect (ie trying to have no water going down emergency drain) or you're over compensating each direction. Fwiw, I always keep a small trickle going through my emergency drain as well. If the main line is starting to get clogged up and there is significant water going down the emergency line it makes lots of noise (good alert). Getting it "perfect" is terribly frustrating. My ATO pushes a bit of extra water down the emergency drain while it is running, but this is definitely not a concern.

Thanks everyone :)

I guess I will have a small trickle going down the drain since I don't want to keep on adjusting the water level every now and then. I will have to extend the emergency drain to submerge inside the water now since I left it over the water level to make a warning sound :razz: